The present invention relates to machines having a hydrostatic transmission or ground drive pump such as a tractor, and more particularly, to a drive control having a combined rocking foot pedal assembly and shift assembly for effecting forward and reverse motion of the machine.
It is conventional to provide tractors and similar machines with hydrostatic transmissions for controlling the speed, direction, and pulling power of the tractor. The transmission is typically provided with a rotatable shift arm or lever which may be rotated in one direction for forward motion of the tractor and in the opposite direction for rearward or reverse motion. The speed of the tractor is proportional to the rotation of the shift arm while the tractor engine is operated at a speed set by a conventional throttle device.
Tractors of this type have also been provided with a rotatable control lever which may be indirectly connected to a rocking foot pedal so that the control lever is rotated in one direction when the pedal is rocked forward for forward motion of the machine and is rotated in the opposite direction when the pedal is rocked rearward for reverse motion of the machine. The speed of the tractor is proportional to the amount the foot pedal is depressed.
A problem with these prior art constructions is that they do not include a mechanism which will permit the control lever of the transmission to remain in a selected position during braking. That is, the control lever is shifted to neutral either manually or automatically whenever the brake is applied, and the control lever must again be shifted to the desired forward or reverse position before proceeding after braking.
This problem is solved in the combined rocking foot pedal assembly and shift assembly of this invention which maintains the control shift lever in a selected position, regardless of foot pedal movement. The present invention permits the shift lever to be maintained in a selected position when manual or automatic operation of the foot pedal occurs, so that the operator is not required to shift into the desired forward or reverse position before proceeding again.